Stainless Steel Coil Tube for HVAC Fan Coil Unit Applications
Product Overview
The Stainless Steel Coil Tube (Product Ref. No. 871) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous coil-form tubing designed specifically for heat exchanger assemblies in Fan Coil Unit (FCU) air conditioning systems. This product serves as the core thermal transfer element within air handling and ventilation infrastructure, enabling efficient heat exchange between air streams and refrigerant or hot water circuits. The coil tube is supplied in continuous coil configuration to facilitate automated coil winding and assembly processes, minimizing material waste and ensuring uniform dimensional consistency throughout the production run.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, predominantly conforming to AISI 304 (UNS S30400) and AISI 316L (UNS S31603) grades, selected for their exceptional corrosion resistance, thermal conductivity, and mechanical durability under cyclic thermal loading conditions.
- Chemical Composition (AISI 304): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%, Phosphorus (P) ≤ 0.045%, Sulfur (S) ≤ 0.030%
- Chemical Composition (AISI 316L): Carbon (C) ≤ 0.03%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%
- Tensile Strength: ≥ 515 MPa (AISI 304) / ≥ 485 MPa (AISI 316L)
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40%
- Thermal Conductivity: 16.3 W/(m·K) at 100°C
- Operating Temperature Range: −196°C to +870°C
- Corrosion Resistance: Superior resistance to atmospheric, chemical, and marine environments; Mo-containing 316L grade offers enhanced pitting and crevice corrosion resistance
Specifications
| Parameter | Specification |
|---|---|
| Product Category | Stainless Steel Coil Tube (Continuous Coil Form) |
| Product Reference No. | 871 |
| Applicable Standards | ASTM A269, ASTM A270, EN 10217-7, GB/T 12771, GB/T 13296 |
| Outer Diameter (OD) | φ6.0 mm – φ25.0 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Diameter | φ500 mm – φ1500 mm |
| Coil Length per Roll | 20 m – 100 m (configurable) |
| Surface Finish | 2B (Cold Rolled and Annealed) / No.4 Brushed / Mirror (BA) |
| End Form | Plain / Beveled / Flanged (upon request) |
| Winding Configuration | Single-layer helical coil / Multi-pass serpentine coil |
| Pressure Rating | Up to 1.6 MPa (design-dependent) |
| Heat Exchange Efficiency | ≥ 85% (in optimized coil configurations) |
| Service Life | ≥ 20 years under normal HVAC operating conditions |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Hot-Rolled Coil (HRC) Source Material Preparation: Virgin stainless steel slabs are hot-rolled into strip form and annealed to relieve internal stresses and establish a uniform austenitic microstructure.
- Cold Rolling and Annealing: The strip undergoes precision cold rolling to achieve the target thickness tolerance (±0.02 mm), followed by controlled furnace annealing at 1050–1150°C to restore ductility and refine grain structure.
- Pickling and Passivation: The annealed strip is acid-pickled to remove oxide scale, then passivated to form a protective chromium oxide passive layer, ensuring optimal corrosion resistance.
- Tube Forming (Seamless or Welded): The strip is formed into tubular cross-section via either seamless piercing (for higher-grade seamless coil tube) or high-frequency induction welding (HF-W) with precision tube-rolling dies.
- Dimensional Calibration and Sizing: Multi-roller sizing stands ensure roundness, straightness, and dimensional conformity within ±0.05 mm tolerance.
- Coil Winding: The finished tube is wound into the specified coil configuration using programmable coil-winding machinery, with controlled winding tension to prevent deformation and inter-coil contact damage.
- Final Quality Inspection: Each coil undergoes 100% visual inspection, ultrasonic testing (UT) for wall thickness and internal defects, hydrostatic pressure testing, and spectrometric chemical analysis verification.
Applications
The coil tube is integral to the following engineering systems and applications:
- Fan Coil Units (FCU): Serves as the primary heat exchanger coil in commercial and residential HVAC systems, facilitating heating, cooling, and dehumidification through controlled air-water heat exchange. The coil tube configuration directly influences the thermal performance and energy efficiency of the intelligent control scheme of the FCU air conditioning system.
- Air Handling Units (AHU): Used in chilled water and hot water coil assemblies for large-scale commercial air conditioning.
- Chilled Beam Systems: Displacement air systems utilizing stainless steel coil tubes for latent and sensible heat control.
- Industrial Process Cooling: Precision temperature control in pharmaceutical, food processing, and semiconductor manufacturing facilities.
- Marine and Offshore HVAC: Corrosion-resistant coil assemblies for marine vessel and offshore platform climate control, leveraging the superior chloride resistance of AISI 316L grade.
- Refrigeration Condenser and Evaporator Coils: In commercial refrigeration systems requiring long-term durability and hygienic surface properties.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework with the following certifications and compliance standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking — Conformity with European Union safety, health, and environmental protection standards
- EN 10204 Type 3.1 — Material Test Certificate (MTC) with independent inspection
- SGS Testing — Third-party material verification and compliance testing
- NACE MR0175 / ISO 15156 — Compliance for sour service applications (316L grade)
- NSF/ANSI 61 — Drinking water system component safety (where applicable)
Unique Selling Points
1. Intelligent HVAC System Compatibility: The coil tube geometry and thermal properties are optimized for integration with advanced intelligent control schemes in fan coil unit air conditioning systems, enabling precise modulation of cooling and heating capacity through variable refrigerant flow and water temperature control strategies.
2. Superior Corrosion and Durability: Austenitic stainless steel construction provides exceptional resistance to condensation-induced corrosion, chemical contamination, and freeze-thaw cycling — significantly extending service life compared to carbon steel alternatives.
3. Hygienic Surface Quality: BA (Bright Annealed) and mirror finish options ensure smooth, non-porous internal surfaces that resist biofilm formation, meeting sanitary requirements for pharmaceutical and food-grade HVAC applications.
4. Precision Dimensional Consistency: Automated coil winding with tight dimensional tolerances ensures uniform heat transfer performance across the entire coil assembly, supporting predictable thermal modeling and control algorithm calibration.
5. Full Traceability: Each coil batch is traceable to its mill heat number, with complete documentation of chemical composition, mechanical properties, and non-destructive testing results.
Summary
The Stainless Steel Coil Tube (Ref. 871) represents a high-performance thermal exchange component engineered for demanding HVAC and industrial air conditioning applications. Its material integrity, dimensional precision, and manufacturing quality ensure reliable long-term performance in intelligent fan coil unit systems, supporting energy-efficient building climate control strategies aligned with modern sustainable engineering practices.